Expose audited hardcoded tunables as plugin config

The audit swept every packages/*/* plugin for the new AGENTS.md
convention (no hardcoded tunables in plugins) and exposes each finding
as a defaulted, validated Config field. Defaults are the previously
hardcoded values throughout, so no deployment or golden changes.

- tool-fs (had NO Config): readLimit, readMaxLineLength, readMaxBytes,
  readStreamMinSize. The caps thread through ReadToolCaps/ReadWindow —
  read-render already documented that the consumer applies the caps, so
  they become explicit per-request fields.
- tool-web: searchMaxResults (WEB_SEARCH_MAX_RESULTS stays as the
  schemastery default). Also fixes the stale GREP_LIMIT references in
  search.ts and the web-capability-seam RFC (no such constant exists).
- bash-local: graceMs (SIGTERM->SIGKILL escalation grace). The
  RunInternals.graceMs test seam is gone: graceMs is now a required
  SpawnSpec field filled from config, so tests exercise the real
  config path and the defaults live in exactly one place.
- subagent-acp: disposeEofGraceMs / disposeGraceMs. The AcpRunSpec
  fields become required for the same one-defaulting-layer reason.
- session-persistence-sqlite: journalMode ('wal' default; the
  rollback-journal modes serve filesystems where WAL's shared-memory
  files do not work, e.g. network mounts).
- hooks-claude + hooks-codex: stderrSummaryMaxChars for the persisted
  hook/result stderr summary. The duplicated summarize() helpers merge
  into hook-protocol's summarizeStderr(stderr, maxChars), beside the
  HookResultRecord field it feeds, with the bound parameterized the
  same way runHook's defaultTimeoutMs already is.
- compact-basic: charsPerToken for the token estimator (default 4, the
  English-text heuristic; CJK-heavy deployments need ~1-2 or compaction
  fires far too late). Also corrects the BasicCompactService class doc,
  which claimed defaults the required-field config never had.
- fs-local: deletes the dead STREAM_MIN_SIZE constant and the dead
  FsIoInternals.streamMinSize seam — the read-routing bound lives in
  the consumer (tool-fs), where it is now config. This is item 1 of
  the proposed prune-write-only-fs-surface RFC, annotated accordingly.

Every new field gets range validation (following the existing
assertPositiveFinite pattern), a README row, and tests covering the
configured behavior, the schema default, and load-time rejection.

packages/bash/bash-local/src/run.ts

@@ -73,6 +73,8 @@ export interface SpawnSpec {
   timeoutMs: number
   /** Per-stream in-memory cap; overflow spills to disk (tail kept in memory). */
   maxOutputBytes: number
+  /** Grace period between the SIGTERM and the SIGKILL escalation on a kill. */
+  graceMs: number
   /** Abort signal — kills the process group when fired. */
   signal?: AbortSignal | undefined
   /**
@@ -100,15 +102,13 @@ export interface SpawnOutcome {
   stderr: CollectedOutput
 }
 
-/** Injectable knobs so tests can exercise escalation/spill without long waits. */
+/** Injectable knobs so tests can exercise spill behavior without the OS tmpdir. */
 export interface RunInternals {
-  /** Grace period between SIGTERM and SIGKILL on the process group. */
-  graceMs?: number
   /** Directory for spill files (defaults to the OS temp dir). */
   spillDir?: string
 }
 
-/** Default SIGTERM→SIGKILL grace period (matches OpenCode's 3s). */
+/** Default SIGTERM→SIGKILL grace period (the `graceMs` config; matches OpenCode's 3s). */
 export const DEFAULT_GRACE_MS = 3_000
 
 let spillCounter = 0
@@ -292,7 +292,6 @@ export interface RunningBash {
  * no inherited shell state); revisit when real workflows demand it.
  */
 export function runBash(spec: SpawnSpec, internals: RunInternals = {}): RunningBash {
-  const graceMs = internals.graceMs ?? DEFAULT_GRACE_MS
   const spillDir = internals.spillDir ?? privateSpillDir()
 
   if (spec.signal?.aborted) {
@@ -331,7 +330,7 @@ export function runBash(spec: SpawnSpec, internals: RunInternals = {}): RunningB
   const kill = (): void => {
     if (graceTimer !== undefined) return // escalation already in flight
     killGroup(pid, 'SIGTERM')
-    graceTimer = setTimeout(() => { killGroup(pid, 'SIGKILL') }, graceMs)
+    graceTimer = setTimeout(() => { killGroup(pid, 'SIGKILL') }, spec.graceMs)
   }
 
   if (spec.timeoutMs > 0) {